JP4259164B2 - Quality monitoring device and quality monitoring method for continuous cast slab - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quality monitoring device which determines the amount of inclusions in cast slabs in real time for every cast slabs by taking the information on the refining process of molten steel which is the upper stream process of a continuous casting process into consideration as well. <P>SOLUTION: The problem described above is solved by the quality monitoring device for the continuous cast slabs provided with a means 8 for finding the determination standard for the amount of the deoxidation product produced in the refining process for molten steel, a means 8 for finding the determination standard for the floating amount of the inclusions within a tundish of a continuous casting process, a means 8 for finding the determination standard for the entangling amount of the mold powder within the casting mold of the continuous casting process, a means 8 for deciding whether the rolling of the cast slab in an unmended state is permissible or not by comparing the above three found determination standards with acceptance standard for the cast slab quality. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a quality monitoring device capable of determining the quality of a continuous cast slab in real time for each slab, and to a quality monitoring method of a continuous cast slab using this quality monitoring device.
[0002]
[Prior art]
In continuous cast slabs of steel, surface defects such as vertical cracks, horizontal cracks, blades and blowholes occur in the surface layer, and non-metallic inclusions (hereinafter referred to as “inclusions”) are present in the interior. In addition, internal defects such as center segregation occurred, which caused quality defects such as surface defects in the final product after rolling, and were a main cause of a decrease in yield of the final product. Therefore, the slab in which the defect more than the allowable amount has occurred on its surface has been removed by surface care such as surface cutting of the slab surface before rolling.
[0003]
By the way, from the viewpoint of energy saving and resource saving, the high-temperature continuous cast slab immediately after casting is directly transferred to a hot rolling mill without maintenance or directly transferred to a heating furnace and heated to a predetermined temperature. The so-called hot direct feed rolling process, in which rolling is performed after the temperature has been raised, has been widely performed. When a steel sheet is produced by a hot direct rolling process, the slab needs to be free of these defects, and various means for avoiding these defects have been developed. For example, vertical cracks are mitigated by the development of mold powder that reduces heat removal in the mold, and inclusions reduce slag oxidation (slag modification) and electromagnetic force on the molten steel in the ladle. It is mitigated by the flow control of the molten steel used in the mold. As a result, these defects are greatly reduced, contributing not only to an increase in the amount of hot direct rolling process, but also to an increase in the surface maintenance of slabs across a wide range of steel types.
[0004]
However, in the continuous casting process that handles molten steel, even if the casting operation was performed as standard, forced operation deviating from the standard operation was forced due to sudden disturbance, for example, the clogging of the immersion nozzle with Al ₂ O ₃ , etc. Occasionally a slab of the desired quality level cannot be produced. When the slab of this part is rolled by a hot direct feed rolling process, or when it is directly fed to the rolling step without cooling after cooling and rolled, the risk of quality defects in the final product becomes extremely high. Therefore, it is necessary to carry out operational changes such as excluding the slab of this part from the hot direct feed rolling process or unrolled rolling target and performing surface maintenance.
[0005]
In order to operate such a slab, it is necessary to monitor and judge the quality of each slab in real time to determine whether a hot direct feed rolling process or unmaintained rolling is possible. Therefore, several means for determining the quality of the slab in real time online have been proposed.
[0006]
For example, in Patent Document 1, detection information detected by a sensor group that monitors an operation status arranged in a tundish, an immersion nozzle, or a mold is input to a control computer, and the current operation status is grasped from the detection information. The current operation is compared with the optimum casting conditions based on the quality requirement information, and the quality is judged whether the current operation satisfies the quality requirement level. If the quality requirement level is not satisfied, the quality is determined. A quality control method for controlling to an optimum casting condition that satisfies the requirements is disclosed, and Patent Document 2 discloses the amount of molten steel surface level fluctuation in the mold and the opening of a regulator for pouring molten steel into the mold from the tundish. A quality determination method is disclosed in which the slab of the part is determined to be normal when the molten metal level fluctuation amount and the opening fluctuation amount are smaller than predetermined values.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-47453
[Patent Document 2]
JP 2000-233265 A [0009]
[Problems to be solved by the invention]
However, as disclosed in Patent Document 1 and Patent Document 2 described above, in the conventional slab quality determination method, the quality of the slab is determined only from information regarding the behavior in the tundish and in the mold, and continuous casting. The information of the refining process of the molten steel which is the upper process of the process is not taken into consideration. Among the quality of the continuous cast slab, the amount of inclusions is not particularly determined only by the continuous casting process, but is also governed by the refining process. Therefore, it is difficult to say that the quality judgment of the slab has been accurately and accurately performed by the conventional quality judgment method.
[0010]
The present invention has been made in view of the above circumstances, and the object of the present invention is to consider the amount of inclusions in the slab in real time for each slab in consideration of information on the refining process of molten steel, which is the upper process of the continuous casting process. And a quality monitoring method for continuous cast slabs using this quality monitoring device.
[0011]
[Means for Solving the Problems]
The quality monitoring device for continuous cast slabs according to the first invention of the present application for solving the above-mentioned problems is the oxygen concentration in molten steel at the end of converter refining, the oxygen concentration in molten steel after vacuum decarburization refining in secondary refining, based on one or more data among the Al oxide amount calculated from in these molten steel oxygen concentration, means for determining determining measure of deoxidation products generated amount of molten steel refining process, the tundish The amount of inclusion floating in the tundish in the continuous casting process based on one or more of the following data: molten steel retention amount, molten steel surface height in the tundish, and average residence time in the tundish One or two of the means for obtaining a judgment scale, the amount of fluctuation of the molten metal level in the mold, the difference in height between the positions of the molten metal on the left and right sides of the immersion nozzle, and the temperature of the mold copper plate measured by the temperature measuring element embedded in the mold copper plate Based on more than species data There are, by matching means for obtaining a judgment measure of mold powder entrainment amount of the mold of the continuous casting process, the three slab acceptance criteria of quality determined each decision metric for each order obtained, the slab Means for determining whether or not rolling can be performed without maintenance.
[0012]
According to a second aspect of the present invention, there is provided a quality monitoring device for a continuous cast slab according to the first aspect of the present invention, wherein the mold powder entrainment amount is determined based on a mold copper plate temperature measured by a temperature measuring element embedded in the mold copper plate. It is obtained based on the temperature distribution form in the mold width direction.
[0013]
The continuous cast slab quality monitoring method according to the third aspect of the invention is determined by the continuous cast slab quality monitoring device according to the first aspect or the second aspect of the invention as to whether or not rolling can be performed without maintenance. The determination result is characterized in that only a passing slab is directly sent to the rolling process without care, and the unsuccessful slab is operated separately without being sent directly to the rolling process.
[0014]
Since the quality monitoring method of the continuous cast slab according to the present invention determines the amount of inclusions in the slab not only in the continuous casting process but also in the amount of deoxidation products generated in the molten steel refining process, it is accurately determined. In addition, the amount of slab inclusions can be determined with high accuracy. Moreover, since the index used as the scale of determination in each process is narrowed down to one particularly important and each is independent, the amount of slab inclusions can be determined without using complicated logic. In addition, the “rolling without maintenance” in the present invention is not limited to the hot direct feed rolling process, but also covers the process in which the slab is cooled and transported to the rolling process without heating and rolled after heating. Literally, it covers all processes of rolling without maintenance.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an example of an embodiment of the present invention, and is a schematic diagram of an overall configuration when a quality monitoring method for a continuous cast slab according to the present invention is carried out.
[0016]
As shown in FIG. 1, the present invention heats a molten steel refining process 1, a continuous casting process 2 for casting the molten steel produced in the refining process 1, and a continuous cast slab manufactured in the continuous casting process 2. It is applied to a manufacturing process of a steel product composed of a rolling process 3 that performs hot rolling, and operation data of a refining process 1 and a continuous casting process 2 are input to a steelmaking process control computer 8. The quality of each one is determined in real time. The steelmaking process control computer 8 is a computer that manages information from the refining process 1 to the continuous casting process 2. Order information such as product standards and delivery dates is input from an integrated management computer (not shown). A part of the function of the process control computer 8 is used as a quality monitor for a continuous cast slab according to the present invention. The molten steel refining process 1 is usually composed of converter refining and secondary refining.
[0017]
The operation data of refining process 1 includes the amount of steel refining in the converter, the refining time, the amount of oxygen used, the composition of the molten steel at the end of converter refining, the slag thickness in the ladle, and whether or not the slag in the ladle is modified. In the next refining, for example, the processing time in the RH vacuum degassing facility, the ultimate vacuum, the molten steel component at the end of refining, and the like are input. The steelmaking process control computer 8 grasps the generation amount of deoxidation products (Al ₂ O ₃ ) generated when molten steel is deoxidized with Al from the input operation data of the refining process 1. Using the operation data that can be determined, a determination scale that is a scale for determining the amount of deoxidation product generated is calculated and obtained.
[0018]
The operation data that can grasp the amount of deoxidation products generated include oxygen concentration in molten steel at the end of converter refining, and vacuum decarburization refining using RH vacuum degassing equipment after converter refining. The oxygen concentration in the molten steel after vacuum decarburization refining, and the amount of Al oxidation calculated from these oxygen concentrations can be used. Based on these operational data, the steelmaking process control computer 8 obtains a determination scale for the amount of decarburized product generated in the molten steel. In obtaining the judgment scale, the steel grades are classified into several categories according to the standards of carbon concentration, Si concentration and Al concentration of steel products, and threshold values are set for each classified steel grade, and the input operation data is compared with the threshold values. The determination scale is calculated based on the degree of deviation from the threshold. In this case, for example, the lower the oxygen concentration in the molten steel, the smaller the determination scale, and the smaller the determination scale, the smaller the amount of deoxidation product generated.
[0019]
The operation data of the continuous casting process 2 includes the amount of molten steel retained in the tundish 4, the molten steel temperature, the molten steel surface height, and the tundish at the tip of the long nozzle for blocking between the ladle and the tundish 4 from the air. The immersion depth in the inner molten steel, the position of the molten metal surface in the mold 5, the amount of molten metal fluctuation, the temperature of the mold copper plate, and the amount of Ar blown into the immersion nozzle for blocking the space between the tundish 4 and the mold 5 from the air Etc. are entered. The steelmaking process control computer 8 can place the tundish 4 in the tundish 4 by using the operation data that can grasp the amount of inclusion floating in the tundish 4 from the input operation data of the continuous casting process 2. While calculating and obtaining a determination scale that is a scale for determining the amount of inclusion floating, the operation data that can grasp the amount of mold powder in the mold 5 is used, and the mold powder is entrained in the mold 5. A determination scale that is a scale for determining the amount is calculated and obtained.
[0020]
As operation data that can grasp the amount of inclusion floating in the tundish 4, the molten steel retention amount and the molten steel surface height in the tundish 4 can be used. Moreover, you may use the average residence time in the tundish 4 which becomes settled from the molten steel residence amount in the tundish 4 and the drawing speed of a slab. Furthermore, the molten steel temperature in the tundish 4 may be a function associated with these operation data. Based on these operation data, the steelmaking process control computer 8 obtains a determination scale for the amount of inclusion floating in the tundish 4. When obtaining the judgment scale, as described above, classify the steel types into several standards for the carbon concentration, Si concentration and Al concentration of the steel product, set a threshold value for each classified steel type, and enter the operation The data and the threshold value are compared, and a determination scale is calculated based on the degree of deviation from the threshold value. In this case, for example, the larger the retained steel amount or the longer the average residence time, the smaller the determination scale, and the smaller the determination scale, the greater the amount of inclusion floating, and the smaller the amount of inclusion in the slab.
[0021]
As operation data that can grasp the amount of mold powder entrained in the mold 5, it is possible to grasp from the amount of fluctuation of the molten metal level in the mold 5 and the height difference between the left and right molten metal surface positions across the immersion nozzle. Although possible, it is preferable to use a mold copper plate temperature measured by a temperature measuring element embedded in the width direction of the mold copper plate from the viewpoint of accurately grasping the entrainment of the mold powder. Below, the relationship between mold copper plate temperature and mold powder entrainment is demonstrated.
[0022]
The present inventors conducted measurements, model experiments, and numerical analysis in an actual machine, and investigated the relationship between the molten steel flow situation in the mold and the mold copper plate temperature distribution form in the mold width direction at various casting conditions. . FIG. 2 schematically shows a comparison between the flow state of molten steel in the mold and the distribution form of the mold copper plate temperature. In FIG. 2, 10 is a mold short-side copper plate, 11 is a molten steel surface in the mold, 12 is an immersion nozzle, 13 is a discharge hole, 14 is a discharge flow, and the discharge flow 14 is indicated by an arrow in the direction of the flow. It represents.
[0023]
In the pattern 0, the surface along the long side copper plate has a gentle upward flow over the entire mold width direction, and a large difference does not appear in the measured values of the temperature measuring elements in the mold width direction. That is, when the temperature peak does not appear remarkably, the mold temperature distribution form is flat across the entire mold width. On the other hand, in the pattern 1, the upward flow in the vicinity of the immersion nozzle 12 associated with the floating of Ar blown into the immersion nozzle 12 becomes dominant, and on the molten steel surface 11, from the immersion nozzle 12 toward the mold short side copper plate 10. Molten steel flows. For this reason, the temperature distribution in the mold copper plate width direction becomes high in the vicinity of the immersion nozzle 12, and one large temperature peak is generated in the vicinity of the immersion nozzle 12. In the pattern 2, the inertia force of the discharge flow 14 from the immersion nozzle 12 is large, the discharge flow 14 branches up and down after colliding with the mold short side copper plate 10, and the molten steel surface 11 is immersed from the mold short side copper plate 10. It becomes a molten steel flow toward the nozzle 12. In this case, the molten steel flow velocity at the molten steel surface 11 is relatively fast. At this time, the temperature of the copper plate in the vicinity of the mold short-side copper plate 10 is high, and a large temperature peak is present in the vicinity of the left and right mold short-side copper plates 10.
[0024]
As described above, the temperature distribution forms can be roughly divided into three types of patterns 0, 1, and 2. However, there are actually temperature patterns other than these three types of patterns. For example, the pattern 3 shown in FIG. 2 occurs when the upward flow in the vicinity of the immersion nozzle 12 accompanying the floating of Ar and the inertial force of the discharge flow 14 are dominant, and the vicinity of the immersion nozzle 12 and the mold short. A temperature peak appears in the vicinity of the side copper plate 10, and a temperature distribution form having three temperature peaks is obtained. However, this pattern can be considered as a combination of pattern 1 and pattern 2. In other cases, it was confirmed that the pattern 0, the pattern 1, and the pattern 2 were represented by combinations.
[0025]
From the above investigation, it was found that the molten steel flow situation varied depending on the casting conditions, and that there were various temperature distribution forms corresponding to this molten steel flow situation. And when determining the mold powder entrainment on the surface of the slab, it was found that it is important and possible to determine from the corresponding temperature distribution form in consideration of these flow conditions.
[0026]
First, the case where the molten steel flow state is pattern 1 will be described. When the molten steel flow state is pattern 1, the floating of Ar is concentrated in the vicinity of the immersion nozzle 12, and the diameter of the rising Ar bubble is large. When the bubbles leave the molten steel surface 11, the molten steel surface 11 is disturbed and mold powder is wound up, or the bubbles themselves are captured and cause blow defects. At this time, the maximum value (T _max ) in the temperature distribution in the width direction of the mold copper plate as shown in FIG. 3A is considered as one factor representing the magnitude of the turbulence of the molten steel surface 11 due to Ar. Therefore, when the maximum value (T _max ) is too large, the entrainment of mold powder by Ar can be predicted.
[0027]
Further, when both a fast flow and a slow flow are present on the molten steel surface 11, the gradient of the molten steel flow velocity is related to the shear stress acting on the mold powder, and the larger the gradient value, the easier the mold powder is cut. The gradient of the flow velocity is detected as the gradient of the mold copper plate temperature. Therefore, as shown in FIG. 3 (b), around the immersion nozzle 12, the maximum value of the temperature distribution in the mold width direction left minimum value (T _L1) (T _L2) by subtracting the value (T _L1 -T _L2 ) And the value (T _R1 −T _R2 ) obtained by subtracting the minimum value (T _R2 ) from the maximum value (T _R1 ) of the temperature distribution on the right side of the mold width direction (hereinafter referred to as “maximum high and low temperature”). Can be considered as another factor that represents the magnitude of the turbulence of the molten steel surface 11 caused by Ar. Therefore, the entrainment of the mold powder by Ar is also affected by the magnitude of the maximum temperature difference. Can be predicted.
[0028]
Next, the case where the molten steel flow state is pattern 2 will be described. When a molten steel flow having a relatively fast flow exists on the molten steel surface 11 as in the pattern 2, the mold powder covering the molten steel surface 11 may be scraped by this flow. If the molten steel flow rate is fast, the mold copper plate temperature also becomes high. Therefore, the maximum value (T _max ) of the temperature distribution in the width direction of the mold copper plate as shown in FIG. 4 (a) can be considered as a factor representing the maximum speed of the molten steel on the molten steel surface 11, and therefore the maximum If the value (T _max ) is too large, it can be predicted that the mold powder will be shaved.
[0029]
In addition, when the molten steel flow situation is pattern 2, when both a relatively fast flow and a slow flow exist on the molten steel surface 11, the gradient of the molten steel flow velocity is related to the shear stress acting on the mold powder as described above. However, the larger the gradient value, the easier the mold powder is cut. The gradient of the flow velocity is detected as the gradient of the mold copper plate temperature. Therefore, as shown in FIG. 4 (b), the maximum value of the temperature distribution in the mold width direction left around the immersion nozzle 12 from the minimum value (T _L1) (T _L2) by subtracting the value (T _L1 -T _L2) And the value (T _R1 -T _R2 ) obtained by subtracting the minimum value (T _R2 ) from the maximum value (T _R1 ) of the temperature distribution on the right side of the mold width direction, the larger value, that is, the maximum height difference is the flow velocity. It can be considered as a factor representing the magnitude of the gradient, and therefore, the presence or absence of cutting of the mold powder can be predicted by the magnitude of the maximum temperature difference.
[0030]
Furthermore, when the molten steel flow state is pattern 2, when the variation in molten steel flow velocity of the molten steel surface 11 on the left and right in the mold width direction is large, a vortex is likely to be generated where the flow collides, and mold powder may be involved. Therefore, as shown in FIG. 4C, the absolute value of the difference between the maximum value (T _L1 ) of the left side temperature distribution in the mold width direction and the maximum value (T _R1 ) of the right side temperature distribution around the immersion nozzle 12 ( (Hereinafter referred to as the “maximum left / right temperature difference”) can be considered as a factor representing the degree of drift affecting the entrainment of the mold powder due to the vortex. Presence or absence of inclusion can be predicted.
[0031]
Further, when the flow state of the molten steel in the mold changes, for example, from pattern 1 to pattern 3, or even in pattern 2, the flow rate of the discharge flow 14 on one side is faster than the other, the inside of the mold The molten steel flow is disturbed, and the amount of fluctuation of the molten steel surface 11 increases, and the probability of occurrence of mold powder entrainment increases. Usually, the flow fluctuation observed in the mold changes gently with its period set to several tens of seconds, but when it changes in a time shorter than this period, the occurrence frequency of mold powder entrainment increases. This change in molten steel flow is detected as a temperature fluctuation amount per unit time of the mold copper plate temperature. Therefore, the maximum value of the temperature fluctuation amount per unit time of the mold copper plate temperature in the mold width direction is grasped, and this maximum The presence or absence of mold powder entrainment can also be predicted based on the magnitude of the value.
[0032]
By the way, when determining the entrainment of the mold powder from the measurement result of the mold copper plate temperature, the temperature measurement position of the mold copper plate is in the range of 10 to 135 mm away from the position of the molten steel surface 11 in the mold in the slab drawing direction. There is a need to. In the range of less than 10 mm from the molten steel surface position, the temperature of the mold copper plate rises and falls due to the fluctuation of the molten steel surface 11 during casting. Therefore, it is impossible to accurately grasp the change in the mold copper plate temperature due to the molten steel flow. This is because, at a position below 135 mm from the surface 11, the amount of change in the mold copper plate temperature due to the change in molten steel flow decreases, and the amount of change in the mold copper plate temperature cannot be accurately grasped. Moreover, it is preferable to install temperature measuring positions at intervals of 200 mm or less in the mold width direction. 3 is a diagram schematically showing the width direction distribution of the mold copper plate temperature and the maximum and minimum values of the mold copper plate temperature when the molten steel flow state is pattern 1. FIG. 4 shows the pattern of the molten steel flow state. 2 is a diagram schematically showing a width direction distribution of a mold copper plate temperature and a maximum value and a minimum value of the mold copper plate temperature when 2. FIG. In the case of pattern 0, there is no molten steel flow rate on the molten steel surface 11 enough to cause the mold powder to be entrained, and no mold powder is entrained.
[0033]
The steelmaking process control computer 8 obtains a determination scale for the amount of mold powder entrapped in the mold 5 using the method described above from the measured value of the mold copper plate temperature. When calculating the judgment scale, the type of mold powder to be used is classified into several groups for each chemical composition and viscosity in the molten state, and a threshold value is set for each classified group. And a determination scale is calculated according to the degree of deviation from the threshold. In this case, for example, the smaller the maximum height difference, the smaller the determination scale, and the smaller the determination scale, the smaller the amount of mold powder involved.
[0034]
The steelmaking process control computer 8 determines the deoxidation product generation amount, the inclusion floating amount, and the mold powder entrainment amount determined in this way, and the slab determined for each order input from the consistent management computer. The quality pass / fail criterion is checked to determine whether or not the corresponding slab can be rolled without being maintained, and the pass / fail judgment result is transmitted to the slab distribution control computer 9. The slab physical distribution control computer 9 that has received the pass / fail judgment sorts the slabs that are accepted and rejected in the sorting step 6. The pass / fail criterion is determined for each order. For example, in the case of a strict surface material, a determination scale serving as a pass / fail boundary value can be set to a small numerical value.
[0035]
The passed slab is directly sent to the rolling step 3 without being maintained, heated to a hot direct feed rolling process or a heating furnace, and then rolled into a product as originally planned. On the other hand, the rejected slab is temporarily placed in the slab cooling field 7 and its operation is determined according to the degree of rejection. That is, when the degree of rejection is small, visual inspection of the slab surface and partial scouring or separate operation processing are performed, and when the degree of rejection is large, front surface slab cutting on the slab surface is performed. Care treatment and scrapping treatment are performed.
[0036]
As described above, the quality monitoring apparatus and quality monitoring method for continuous cast slabs according to the present invention are not limited to continuous casting process 2 but are cast in consideration of the amount of deoxidation products generated in molten steel refining process 1. Since the amount of inclusions in the piece is determined, the amount of inclusions in the slab can be determined accurately and accurately. As a result, a reduction in the defect occurrence rate in the final product is achieved, contributing to a reduction in manufacturing costs. Moreover, since the index used as a determination scale in each process is narrowed down to one particularly important, and each is independent, the inclusion amount of the slab can be determined without using complicated logic.
[0037]
【The invention's effect】
According to the quality monitoring apparatus and quality monitoring method for continuous cast slabs according to the present invention, the amount of inclusions in the slab is determined by taking into account the amount of deoxidation products generated not only in the continuous casting process but also in the refining process of molten steel. Therefore, it is possible to judge the quality of the slab accurately and accurately, and as a result, it is possible to reduce the defect occurrence rate in the final product and contribute to the reduction of manufacturing costs. Effect.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an embodiment of the present invention, and is a schematic diagram of an overall configuration when performing a quality monitoring method for a continuous cast slab according to the present invention.
FIG. 2 is a diagram schematically showing a comparison between a flow state of molten steel in a mold and a distribution form of mold copper plate temperature.
FIG. 3 is a diagram schematically showing a width direction distribution of a mold copper plate temperature and a maximum value and a minimum value of the mold copper plate temperature when the molten steel flow state is pattern 1;
4 is a diagram schematically showing a width direction distribution of a mold copper plate temperature and a maximum value and a minimum value of the mold copper plate temperature when the molten steel flow state is pattern 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Refining process 2 Continuous casting process 3 Rolling process 4 Tundish 5 Mold 6 Sorting process 7 Slab cooling field 8 Steelmaking process control computer 9 Slab distribution control computer 10 Mold short side copper plate 11 Molten steel surface 12 Immersion nozzle 13 Discharge hole 14 Discharge flow

Claims (3)

Data of one or more of oxygen concentration in molten steel at the end of converter refining, oxygen concentration in molten steel after vacuum decarburization refining in secondary refining, and Al oxidation amount calculated from these oxygen concentrations in molten steel Based on the above, out of the means for obtaining a judgment scale for the amount of deoxidation product generated in the refining process of molten steel, the amount of molten steel retained in the tundish, the molten steel surface height in the tundish, and the average residence time in the tundish Based on one or more of the above data, means for obtaining a judgment scale for the amount of inclusion floating in the tundish of the continuous casting process, the amount of molten metal surface fluctuation in the mold, and the position of the molten metal surface on both sides of the immersion nozzle Based on the data of one or more of the mold copper plate temperature measured by the temperature measuring element embedded in the mold copper plate, the determination scale of the amount of mold powder entrained in the mold of the continuous casting process Demand Means that collates said three slab acceptance criteria of quality determined each decision metric for each order obtained, comprising means for determining whether the rolling remain free care of the slab, the A quality monitoring device for continuously cast slabs.   The determination scale of the mold powder entrainment amount is obtained based on a mold width direction temperature distribution form of a mold copper plate temperature measured by a temperature measuring element embedded in the mold copper plate. Quality monitoring device for continuous cast slabs.   The determination result of whether or not to allow unrolled rolling as judged by the quality monitoring device for continuous cast slabs according to claim 1 or claim 2 is a rolling process in which only unsuccessful rolling slabs are left uncleaned. A method for monitoring the quality of a continuously cast slab, characterized in that the directly cast and rejected slabs are operated separately without being directly sent to the rolling process.

Images